Squamous papilloma is the most common benign oral epithelial lesion, and it is well known to be associated with human papilloma virus 6 and 11. Here, we report a case of squamous papilloma associated with human papilloma viruses (HPV)-32 in a 4-year-old boy who presented with a verrucous lesion on the lower lip. HPV-32 is often associated with a rare benign condition focal epithelial hyperplasia (FEH). A limited number of lesions and the absence of characteristic histology ruled out FEH in our patient. To the best of our knowledge, the association of oral squamous papilloma with HPV-32 is hitherto unreported.

Human papilloma viruses (HPV) are DNA viruses that infect the basal epithelial cells of the skin and the mucosa. Oral HPV infections can induce benign oral papilloma, oral condylomas, and focal epithelial hyperplasia (FEH). Oral papilloma can occur at any age, but the most commonly seen in the third or fourth decade of life.[1] Oral papillomas are usually caused by HPV 6 or 11. Here, we report a case of oral papilloma associated with HPV-32, which generally causes FEH.

~ Case Report

A 4-year-old boy from North Kerala was presented with a white coloured warty lesion on the mucosal aspect of the lower lip and upper lip. The lesion initially appeared on the lower lip nearly 2 months ago, gradually increased in size and a similar looking kissing lesion appeared on the mucosal aspect of the upper lip. His medical history was otherwise insignificant with no clinical or laboratory evidence of immunodeficiency. None of his family members had similar lesions. Histopathology of excision biopsy showed a papillomatous tumour with hyperkeratosis, acanthosis, and cells with koilocytic change. It was diagnosed as squamous papilloma [Figure 1].

With these clinical, histological, and virological findings we arrived at a diagnosis of oral squamous papilloma associated with HPV-32. The lesions were cauterised using bipolar cautery. On follow-up after 1-month the lip lesion appeared healed and small satellite sparse lesions were noticed. However, the lesions did not grow further. The patient was advised to be under regular follow-up.

~ Discussion

Oral squamous papilloma is a benign proliferation of stratified squamous epithelium producing papillary or verrucous exophytic mass. The proposed risk factors include HPV infection, betel quid chewing, and smoking.[3] HPV 6 and 11 are implicated as the common causative agents for oral squamous papilloma with 2 and 57 reported as rare associations.[4] However, the association of oral papilloma with HPV 32 as in our case is hitherto unreported.

The genital tract is the reservoir for all mucosal HPVs except 13 and 32, which are viruses of the oral cavity. In certain ethnic groups in American Indians and Eskimos they are associated with a condition known as FEH, also known as Heck's disease or multifocal papilloma mainly affecting the labial and buccal mucosa, lower lip, and tongue.[5],[6] This was known as a disease of children, but during the last decade there were several reports of FEH in patients infected with the human immunodeficiency virus.[5] FEH typically present as multiple smooth, dome-shaped papules lacking a pebbly surface. They usually take on the colour of normal mucosa, but at times may appear white.[5],[7]

The age of our patient, the site of involvement and the viral genotype were consistent with a diagnosis of FEH, but the morphology, the limited number of lesions, absence of similar illness in any of the family members, geographical area of residence, and histology were against FEH.

Histologically, FEH is differentiated from papilloma by its absence of pronounced surface projections and the presence of characteristic mitosoid bodies (nuclei with coarse clumped heterochromatin resembling a mitotic figure).[5],[6]

Oral HPV infection assumes significance for its role in the transmission of the virus between family members.[8] Horizontal or vertical transmission can produce HPV infection in the paediatric age group.[8] We cannot comment on the mode of transmission of infection in our patient, as no virology work up was carried out in his parents and they denied any history of similar looking lesions or verrucous lesions in person or in any of the family members. The different modes of transmission of oral papillomas are not well delineated with most primary lesions occurring spontaneously.[7] There is a paucity of data regarding the time taken for the natural clearance of this infection.

Though occasionally more than one lesion may occur as in our case, typically squamous papillomas are solitary lesions as they are only mildly contagious. Direct mucosal contact is a pre-requisite for transmission. For the virus to invade the basal cells of the epithelium probably an erosion of the recipient mucosal epithelium is warranted.[7] In our case, minor trauma during mastication or through lip biting may have facilitated the entry of the virus from the lower lip to produce lesion on the corresponding site of the upper lip. Current research has not shown any malignant potential for HPV-32.[9]

The treatment options available for oral squamous papillomas are surgical excision, laser ablation, electrocautery, and cryosurgery or intralesional interferon injection. Irrespective of the treatment modality adopted, a microscopic examination is recommended since certain early squamous carcinomas may present as papillomas.[7] In spite of its known non-oncogenic status we advised our case to be under regular follow-up as there is a lack of data on the nature and progression of squamous papilloma induced by HPV-32. To the best of our knowledge, the association of oral squamous papilloma with HPV-32 is hitherto unreported.

Acknowledgements

The authors acknowledge Ms. Aswathy Raj and Mr. Akhil, Research assistants at Manipal Centre for Virus Research for their technical support.

Financial support and sponsorship

The virological part of the work was supported by the ICMR grant No. 5/8/7/15/2010/ECD-I.